Free radical damage has been strongly associated with virtually every chronic degenerative disease, including cardiovascular disease, arthritis and cancer. Clearly, due to the potent antioxidant activity of grapeseed, its therapeutic potential is quite broad. Most clinical studies have been conducted in Europe using a commercial product known as Endotelon®. Due to the poor bioavailability of high-molecular-weight proanthocyanidins, it is advised that products containing chiefly low-molecular-weight PCs be used in practice.
FLUID RETENTION, PERIPHERAL VENOUS INSUFFICIENCY AND CAPILLARY RESISTANCE
Several clinical studies have investigated the use of grapeseed extract in fluid retention, capillary resistance or venous insufficiency, producing positive results.
Hormone replacement therapy and fluctuations in hormone levels can produce symptoms of venous insufficiency in some women. One large study involving 4729 subjects with peripheral venous insufficiency due to HRT showed that grapeseed extract decreased the sensation of heaviness in the legs in just over half the subjects by day 45 whereas 89.4% of subjects experienced an improvement by day 90. According to an open multicentre study of women aged 18-50 years with oedema due to premenstrual syndrome, grapeseed extract (Endotelon®) administered from day 14 to 28 improved various symptoms of fluid retention such as abdominal swelling, weight gain and pelvic pain and also venous insufficiency. The treatment was taken for four cycles, with most women (60.8%) responding after two cycles and 78.8% responding after four cycles.
An open study involving 24 patients with non-complicated chronic venous insufficiency found that over 80% of subjects receiving OPCs (100 mg/day) reported lessened or absent symptoms after 10 days. Symptoms of itching and pain responded best, completely disappearing during the course of treatment in 80% and 53% of the patients respectively. A double-blind study of 50 patients with symptoms of venous insufficiency found that grapeseed extract (Endotelon® 1 50 mg daily) improved both subjective and objective markers of peripheral venous insufficiency such as pain.
In some pathological conditions, such as inflammation or diabetes, vascular permeability can be abnormally increased. Two studies investigated the effects of grapeseed extract on capillary resistance in hypertensive and diabetic patients under both open and double-blind, placebo controlled conditions with treatment producing significant improvements in both groups. The studies used a daily dose of 1 50 mg (Endotelon®).
Grapeseed extract (Endotelon® 150 mg) was found to stabilise diabetic retinopathy in 80% of subjects compared to 47% with placebo, under double-blind test conditions. These results were obtained by measuring objective markers such as visual acuity, muscular tone, and ocular tone.
A double-blind study involving 75 patients with eye strain caused by viewing a computer screen found that grapeseed extract 300 mg daily significantly improved objective and subjective measures. Grapeseed extract (Endotelon®) has also been shown significantly to improve visual adaptation to and from bright light in a dual centre study involving 100 volunteers. A dose of 200 mg daily over 5 weeks was used. It has been proposed that grapeseed extract increases rhodopsin content of the retina or accelerates its regeneration after exposure to bright light.
A randomised, double-blind study of 40 hypercholesterolaemic subjects compared the effects of placebo, chromium polynicotinate (400 µg/day), grapeseed extract (200 mg/day) or a combination of both. Over 2 months, the combination treatment decreased total cholesterol and LDL levels significantly but did not significantly alter homocysteine, HDL or blood pressure among the four groups.
ENHANCES DERMAL WOUND HEALING
A 2002 study in mice found that topical application of grapeseed proanthocyanidins considerably accelerate wound contraction and closure and provided additional support during the wound healing process.
Chloasma is a condition characterised by hyperpigmentation and is generally considered recalcitrant to treatment. Proathocyanidin-rich grapeseed extract successfully reduced hyperpigmentation in women with chloasma after 6 months of oral treatment according to an open study involving 12 subjects. The study continued for another 6 months but failed to find an additional improvement with further use. The researchers suggested that a preventative effect may be possible with long-term oral grapeseed extract when used in the months prior to summer.
It is believed that oxygen-derived free radicals mediate tissue damage in acute and chronic pancreatitis. Therefore, antioxidant treatment is being investigated. A small, open study of three patients with difficult-to-treat chronic pancreatitis found that a commercially available IH636 grapeseed extract produced a reduction in the frequency and intensity of abdominal pain, as well as resolution of vomiting in one patient.
PREVENTING REPERFUSION INJURY
Procyanidin administration reduced the adverse effects of myocardial ischaemia-reperfusion injury during cardiac surgery in several in vivo studies. This appears to be positively associated with an increase in plasma antioxidant activity.
REDUCES SUN BURN
Topical application of grapeseed extract has been shown to enhance sun protection factor in human volunteers.
PROTECTION AGAINST MULTI-ORGAN DRUG AND CHEMICAL TOXICITY
The results from a number of in vivo studies have suggested pre-exposure to grapeseed extract can provide multi-organ protection against damage caused by various drugs such as paracetamol, amiodarone, doxorubicin, cadmium chloride and dimethylnitrosamine treatment.
• Fluid extract 1:1 (g/mL): 20-40 mL per week
• Solid dose forms: 12,000 mg of grapeseed extract standardised to OPCs* taken 2-3 times daily in order to provide 150-300 mg of oligomeric proanthocyanidin complexes (OPCs) daily.
*Due to the poor bioavailability of high-molecular-weight PCs, it is advised that products containing chiefly low-molecular-weight proanthocyanidins be used in practice.